The Government is being urged to keep a pledge to introduce discounted bus and train travel for apprentices.
The TUC said many apprentices are facing a "double whammy" of low pay and high travel costs.
The union organisation complained that a Government promise two years ago to provide travel support has not been delivered.
Cities including London, Liverpool and Manchester have introduced travel discounts for apprentices, but the TUC said there should be a national scheme.
TUC general secretary Frances O'Grady said: "Apprenticeships should be affordable for all, but many apprentices face the double whammy of low pay and high travel costs.
"There's no good reason why apprentices should be left worse off than other students.
"The Government must deliver on its promise to help every apprentice with their travel costs.
"It would help more apprentices complete their studies, and it would ensure Britain has the skills we need for the future."
It comes after the Government launched a new 16-17 railcard on Tuesday , offering half price travel for millions of young people.
